This study could be an important

This study could be an important tool in FRMS [20] implementation, with its multi-layered defensive strategies to manage fatigue, enhancing the importance of crew monitoring in facilitating a higher control in the observed variables. Sleep hygiene techniques/education and fatigue countermeasures are currently contemplated in FRMS [20]. However, these are not yet mandatory policies, resulting in insufficient or lacking implementation in many companies. This study demonstrates the importance of these educational plans to manage sleep and fatigue, considering the high prevalence values obtained for sleep and fatigue.
Introduction The temporal organization of sleep varies among adults [1,2] and adolescents [3,4]. Between-individual differences in the preference for the timing of sleep and other daily activities is usually estimated with self-report questionnaires probing chronotypes, i.e., whether a person prefers to go to bed relatively early in the evening and wake up early in the morning (morningness, Morning-type=M-type) or go to bed late and also wake up late (eveningness, Evening-type=E-type) [1,2]. Most individuals, however, fall somewhere between these opposites and represent the Intermediate type (I-type). Children are prone to morningness [5], but the onset of puberty brings a major change towards eveningness [4,6–9]. However, a small shift back to morningness usually occurs before the age of 20, probably due to social pressure [4]. Recent research suggests that increased sensitivity to light may trigger this FK506 change toward eveningness in puberty [10]. Accordingly, youngsters living in rural areas with no electric lighting exhibit earlier bedtimes than their peers in more urban areas [11,12]. Several lines of recent evidence suggest that eveningness has a negative effect on sleep. Eveningness-typed adolescents report having a poorer quality of sleep than individuals exhibiting other chronotypes [3,7,13], and daytime sleepiness is often [3,14,15], but not always [16], reported by E-types. Short et al. [13] point out that daytime sleepiness or tiredness in E-types is caused by poor sleep quality. Compared to morning-orientated adolescents, E-types are reported to sleep less during the school week [3,7]. Although adults usually sleep for the same length of time on weekday nights irrespective of their chronotypes, E-typed adults complain of insufficient sleep [16,17]. Defining optimal sleep is a matter of considerable complexity [18]; in this study, only subjective sleep need was assessed. The discrepancy between reported sleep length and subjective need for sleep was used to define excessive sleep and sleep deprivation. Mercer et al. [19] found two groups of adolescents with respect to this: those wanting more sleep on weekday nights, and those satisfied with their sleep duration. They suggested that eveningness might explain why the respondents felt they needed more sleep. Compared to other chronotypes, adult E-types have shown equivalent sleep duration on weekday nights, but have expressed not having a sufficient amount of sleep [16]. The present article further tested whether differences exist in bedtime, wake-up time, duration of sleep, subjective sleep need, and tiredness among different chronotypes. Sleep-related factors in adolescence tend to be at least partly gender specific [4,6,20,21], therefore we were also interested in seeking possible differences between male and female participants.
Method
Results Descriptive information is shown in Table 1. The internal consistencies that could be calculated for the measures were acceptable. When school week and weekend sleep were compared, some significant differences were seen. The participants reported that they slept about two hours less on weeknights than weekend nights, t(549)=−26.87, p<.001, and were more tired during the school week, t(553)=29.93, p<.001. Compared to weekends, they also went to bed earlier on weekdays, t(554)=−25.62, p<.001, and woke up earlier, t(549)=−47.17, p<.001.